Đáp án:
${\left\{\begin{aligned}a=\frac{-1}{2}\\ b=-4\\ c=\frac{5}{6}\end{aligned}\right.}\\$
Giải thích các bước giải:
$f(x)=g(x)\\
\Leftrightarrow (4a+5)x^2-3bx+(2c-5) =3x^2+12x-4c \\
\Leftrightarrow {\left\{\begin{aligned}4a+5=3\\ -3b=12\\ 2c-5=-4c\end{aligned}\right.}\\
\Leftrightarrow {\left\{\begin{aligned}4a=3-5\\ b=\frac{12}{-3}\\ 2c+4c=5\end{aligned}\right.}\\
\Leftrightarrow {\left\{\begin{aligned}4a=-2\\ b=-4\\ 6c=5\end{aligned}\right.}\\
\Leftrightarrow {\left\{\begin{aligned}a=\frac{-1}{2}\\ b=-4\\ c=\frac{5}{6}\end{aligned}\right.}\\$
